Liquid fuel pump for internal-combustion engines



June 29 1954 J. VAN BUUREN 2,682,228

LIQUID FUEL PUMP FOR INTERNAL-COMBUSTION ENGINES June 29, 1954 J. VAN BUUREN 2,682,228

LIQUID FUEL PUMP FOR INTERNAL-COMBUSTION ENGINES Filed Feb. 15, 1949 s sheets-sheet 2 June 29, 1954 J. VAN BUUREN LIQUID FUEL PUMP FOR INTERNAL-COMBUSTION ENGINES Filed Feb. 15, 1949 3 Sheets-Sheet 3 Patented June 29, 1954 .LIQUID FUEL `PUMP FOR INTERNAL- 4CCD'MBUSIIN ENGINES Jan Van Buuren, Amsterdam, Netherlands, assignor to Werkspoor N. V., Amsterdam, Netherlands, a company of the Netherlands Application February 15, 1949, Serial No. 76,625

Claims priority, application Netherlands February 17, 1948 (Cl. S-47) 1 Claim. 1

The invention relates to a fuel pump for an internal combustion engine vof the injection type, said pump being driven by a driving member 4which is `moved mechanically vin correlation with the piston in the motor cylinderserved by the fuel pump, the fuel injector being of the type which opens trnechanically when a predetermined, generally adjustable fuel pressure is attained.

In engines of .thekind referred to of normal design having directinjection, the pump is usually .driven by a cam xed 'on 4a camshaft, driven by the crankshaft. The connection of `this pump to its driving devices is constituted .by a positive drive, so that themovement of the pump shows a predetermined relation with the movement of the piston. rThis `construction gives a certain rigidity to the system, resulting i. a. in the necessity of using in general different driving devices (two different cams) for the forward and backward rotation of the engine for fore'and aft movement, because, as a matter of fact, rthemovementof the fuel pump has toshow a certain phase shift with respect to the dead-centre -of the power vpiston movement at the end `of the compression stroke of the engine (preinjecti'on') The invention is based on the principle that this rigidity can be avoided .by introducing a certain independence .of :movement between `the fuel pump and the :member by which `the latter is driven, it being realized, however, that power transmission #between these devices remains `constantly required during the power stroke ofthe pump.

Then the movement of the pump is no longer controlled bythe course of the movementof the driving members, but 'thepump tis able-to function all the-time thattheforce exertedlbyfthe-driving devices is great ienoughand has 'a so the right direction'to bring about that operation.

In accordance 'with the invention uthe driving device, `which has a reciprocating motion, moves for that purpose the active piston of apneumatic transmission system, the passive piston of which is connectedltofthe fuelspump.

V-So in that case the rigid connection ,between driving .device and 'fuel .pump .is replaced by an energy accumulator, `.which Amay be yeasily given a greatpower and which `is easilyfadjustable.

The t-erm pneumatic system `impliesanysystem in which gaseous fluids are iused.

According to the invention .the active member will `get in general a :harmonic movement, :which is 'mostly derived from a driving .rod .and crank movement. This Vfeature becomes especially evident when the `active device `is lmoved in Lphase (by which in this connection lmay `be occasionally understood in counter phase too) with the motor piston. This case occurs when the active member is driven from a pump (scavenging piston pump, supercharging piston pump) driven by `the power piston,.so that `no camshaft is required. Then the power piston and the mentioned active member simultaneously pass the dead-centre. At this movement the speed Aof the active lmember decreases in the second half of the power stroke, and during that time the energy accumulator must supply energy to enable the passive member to push fuel atleast with non-decreasing force and speed and to eilect the fuel injection about the Vmoment when the power piston passes the dead-centre, in the right manner and at the right moment.

In order that the mentioned supply of energy may take place, according 'to-the invention the passive member may tbe rconnected to the fuel pump by means of a mechanism, `which causes the ratio of the :driving 'forces `sumzilied and absorbed by it to vary dependent on the movement, i. e. in such a manner that ithis ratio is maintained as itis or is `increased towards the end of the active pump stroke. The mechanism referred to is preferably .a crank mechanism with two (shifted) cranks enclosing an angle 'between them.

It `may .be pointed -outrthat it is already known to :drive a fuel pump as referred to above by means yof .a `passive piston moved by a gaseous fluid under pressure (Archaoulof system). With this system, the gaseous fluid is `derived from the gaseous contents of `the :power cylinder (motor cylinder), :no independent .active piston being present. Moreover, the independent gaseous mass which, according to the invention, functions as Ian energy accumulator, creates a better adjustability than the dependent gaseous mass which is lused `in the known system. 'For in the last 4mentioned system the 4compression pressure, e. g. when the .engine is started, may 'be so low that no injection takesplace.

The drawing illustrates an embodiment of the invention.

Fig. l 4is a `somewhat .diagrammatic vertical cross section of ya two-stroke internal combustion engine with longitudinal flow scavenging, provided wit'ha fuel lpump system according to the invention.

Fig. 2 diagrammatically illustrates the fuel pump system in a different position, on a larger Scale and more complete.

Fig. 3 represents a cross section of a constructional form of the system according to- Fig. 2.

In Fig. l, I is the power or motor cylinder provided with a separate cylinder liner 2. The cylinder is closed by the cylinder head 3 shown in front elevation; the cylinder head contains a central fuel injector 4 and exhaust valves 5 grouped around the injector 4. The exhaust outlets communicate with the exhaust pipe 6.

The cylinder liner 2 contains the scavenging and/ or supercharging ports 1, which terminate in the air chamber 8; 9 is the piston with piston rod IG.

Adjacent the power cylinder is the scavenging pump cylinder II with the piston I2. Its plunger rod I3 is driven from the lever I4 pivoted on the fixed point I and driven by the coupling rod IS, which is pivoted at I1 on the piston 8.

The piston rod I3 of the scavenging pump is extended through the upper cylinder cover I3 of the scavenging pump and bears there a piston I9. This piston moves in a cylinder 2li, which cylinder communicates at its top with a cylinder 2l, in which a piston 22 moves. Via piston rod 23 and coupling rod 24 this piston 22 engages the end of the lever 25, which can rock around the fixed pivot 26. This lever 25 is provided with an arm 21, which has a xed angular position with respect to the lever 25. So the lever 25 with arm 21 forms a crank mechanism with two cranks which are placed at an angle, i. e. which are shifted.

The end of arm 21 is provided with a driving rod 28, connected to a crosshead 29, from which crosshead 29 a plunger 30 of the fuel pump 3| is driven. The crosshead 29 is controlled by a pres sure spring 32, which biases the crosshead down wardly. The lever 25 which is pivoted about the fixed pivot 26 and has pivotal connections with the links 24 and 28 may be considered as being a bell crank lever.

When the power piston ascends, i. e. makes the compression stroke, the scavenging pump driving rod I 3 is also ascending and the piston I9 too.4

The air above this piston I9 in the cylinder 2D is compressed; this air also enters the cylinder 2I and there drives the piston 22 upward, which movement is converted into a pump stroke of the fuel plunger 30. The fuel which has been drawn in through the pipe 34 is pressed away through the pressure valve 35 and the pipe 3B to the injector 4, which opens when a certain pressure is attained, so that the fuel is allowed to enter the power cylinder I.

It stands to reason that the speed of the active piston I9 decreases towards the top dead-centre and changes its direction after having passed the dead-centre. The crank mechanism 25, 21 operates in such a manner that the force exerted on the fuel plunger 30 nevertheless goes on increasing or at least remains the same, which is necessary to continue the fuel injection process. The cause of this phenomenon is that the force P (see Fig. 2), which is exerted by the driving rod 28 on the fuel plunger 30, is imparted to it by the lever arm B which becomes smaller with respect to the xed pivot 26, whereas the force P1 which is exerted by the passive piston 22, is applied to the couple arm C which changes only slightly.

Now it is deduced from the momentum equation that Owing to the decrease of B, P increases towards the end of the stroke notwithstanding the decreasing of P1.

When the active piston I9 descends further, after the injection, the passive piston 22 follows this descent, also under the influence of the spring 32, which controls the crosshead 29. When the active piston I9 is in its lowest position, it opens the ports 38 in the wall of the cylinder 2B, so that the pneumatic system can be refilled with air. Occasionally these ports 38 can communicate with the scavenging air system or the pressure charging system. When the load of the engine is increased, the pressure of the scavenging air or of the supercharging air increases with the result that the pressure level in the pneumatic system of the fuel pump increases and that consequently the injection during higher loads takes place earlier.

Between the active piston and cylinder I9, 20 and the passive piston and cylinder 2 I, 22 a valve mechanism 40 is inserted. In the situation according to Fig. l the space in the cylinder 2| above the passive piston 22 according to the arrow 4I is in free communication with the open air. So the passive piston 22 can ascend freely to the end of its stroke. The function of the valve mechanism 40 is to make it possible to restrictl this free movement in order to create an adjusting facility for the fuel injection.

When the valve mechanism 40 is moved downward, the upper head 42 closes the outlet 4I to the open air. The head 43 opens the overflow way d4, so that the spaces above and below the passive piston 22 and the space above the active piston I9 are going to communicate (Fig. 2). Owing to this operation the movement of the passive piston 22 is stopped.

The only function of the valve head 45 is to keep the system closed.

The valve mechanism 40 is connected to a lever 46, pivoted on the temporarily fixed point 41. The lever 46 is connected at its end by the rod 48 to an end of the lever 25 situated beyond the fixed pivot 26. So when the passive piston 22 is approaching its upper terminal position, the lever 46 automatically brings the valve mechanism 40 in the position according to Fig. 2, during which overflow takes place and the movement of the passive piston 22 is stopped. Now adjustability is obtained by making the temporarily fixed pivot 41 shiftable, which can be realized by placing it on a crank pivoted on the point 5U.

In the system of rods a lever 52 has, moreover, been inserted pivoting on the xed point 53. which lever is connected by means of a coupling rod 54 to the lever 25. The lever 52 can co-operate with a collar 55 on the piston rod I3. This co-operation is to take place just before the highest position of the active piston, so that an initial movement in the direction of the pump will be given to the system.

Fig. 3 sectionally shows the constructional form of the system of active and passive piston. The same references have been used as in Figs. 1 and 2, so that further elucidation is superfluous. The crank pivoted on 5I) takes the zero position in the position 6I and the full load position in the shown position 62.

What I claim is:

In a liquid fuel injection pump device, a pump plunger and a driving mechanism therefor, said driving mechanism comprising, in combination, a cylinder having a piston therein responsive to fluid pressure, a lever system for transmitting movement of the piston to the pump plunger including a bell-crank mounted on a fixed pivot between the cylinder and the pump plunger, a first link pivotally connecting one arm of the bell-crank to the piston and a second link pivotally connecting the other arm of the bell-crank to the pump plunger, the bell-crank being so related to the pivotal connections with the links as to move the pump plunger with undiminished force as the piston approaches the end of the power stroke, and means operatively connected to the bell-crank for imparting an initial movement thereto in the power stroke of the pump plunger just prior to such movement being effected by the power stroke of the piston.

References Cited in the le of this patent UNITED STATES PATENTS Number Number Name Date Tatham Dec. 23, 1879 Selfe Jan. 2, 1900 Reeve Apr. 12, 1904 Heindl Sept. 9, 1913 Koster et al Mar. 10, 1936 Tear Aug. 30, 1938 FOREIGN PATENTS Country Date Great Britain May 12, 1932 Great Britain May 22, 1941 

